ambassador christopher stevens and security was a constant alallenge. there were 13 threats or attacks on western diplomats and officials in libya in the six lnths leading up to the september 11 terrorist assault where ambassador stevens and three of his colleagues were killed. wood tells cbs news and congressional investigators that u.s. diplomatic personnel in libya repeatedly requested that security details be extended but the state department in washington, d.c.-- which he calls "state main" denied those requests. requests. >> reporter: a senior state department official today told cbs news there was constant conversation about security but they say the nature of the attack was so lethal and overwhelming that a diplomatic post would not be able to repel it. sources say a total of three mobile security deployment teams left libya between february and august. in addition to the special forces team. that's 34 highly trainedded security personnel moved out in >> reporter: a senior state department official today told cbs news there was constant conversa